Chromatographic column

ABSTRACT

To hold the end fittings to the central column of a chromatographic column, the central column has a different radially-extending flange on each of its ends. A different sleeve fits over each end of the central column and has an inwardlyextending ridge that fits over the flange of the central column but engages a rigid split ring which extends slightly above the flange. The rigid split ring is formed of two parts, each of which forms an arc greater than 180* so that the ring can be assembled around the central column to press an O-ring against the flange when engaged by the ridge. Each end fitting threadedly engages a different sleeve so as to be held in place thereby as pressure in the central column is exerted against it, causing it to pull the sleeve so that the ridge on the sleeve presses the split ring against the O-ring, thus compressing the O-ring against the flange.

Wilhelmson et al.

[ 1 Sept. 9, 1975 1 CHROMATOGRAPHIC COLUMN [75] Inventors: Jack L. Wilhelmson; Douglas M.

Grant, both of Lincoln, Nebr.

[73] Assignee: Instrumentation Specialties Company, Lincoln, Nebr.

[22] Filed: Feb. 18, 1975 [21] App]. No.: 550,420

Primary Examiner-John Adee Attorney, Agent, or FirmVincent L. Carney 5 7 ABSTRACT To hold the end fittings to the central column of a chromatographic column, the central column has a different radially-extending flange on each of its ends. A different sleeve fits over each end of the central column and has an inwardly-extending ridge that fits over I the flange of the central column but engages a rigid split ring which extends slightly above the flange. The rigid split ring is formed of two parts, each of which forms an arc greater than 180 so that the ring can be assembled around the central column to press an O- ring against the flange when engaged by the ridge. Each end fitting threadedly engages a different sleeve so as to be held in place thereby as pressure in the central column is exerted against it, causing it to pull the sleeve so that the ridge on the sleeve presses the split ring against the O-ring, thus compressing the O- ring against the flange.

18 Claims, 4 Drawing Figures CHROMATOGRAPHIC COLUMN This invention relates to chromatographic columns.

One class of chromatographic column includes a central glass column, an outer water jacket around the central column, and end fittings which seal the water jacket and the central column, except for inlets and outlets to recirculate water through the water jacket and except for inlets and outlets for solvent, samples, eluents and the like to enter and leave the central column.

In one prior art type of chromatographic column of this class, the end fittings are mounted permanently to the central column, being held in place by flanges on the central column, which flanges have an outer diameter greater than the inner diameter of the end fittings. This prevents the end fittings from being forced from the chromatographic column by fluid pressure.

This type of prior art chromatographic column has a disadvantage in that, if the central column is broken, an entire new column assembly must be purchased.

In another prior art type of chromatographic column, the ends of the central tube are flared and the end fittings are held by sleeves which press against sealing rings at the flared ends and threadedly hold the end fittings.

This prior art type of chromatographic column has a disadvantage in that it is relatively expensive to fabricate because of the flared ends of the central column. The flared ends are expensive because the inside of the column must be of uniform diameter and consequently the flared portion of the column must have gradually thickened walls.

In still another type of chromatographic column, the central column has a radially-extending flange at only one end to hold the end fittings at the top end of the chromatographic column. The bottom end is supported by the base of the chromatographic column.

This type of chromatographic column has a disadvantage that injuries may result if the ends are accidentally reversed so that the end without a flange is facing upwardly and may be forced from the column under fluid pressure during use of the chromatographic column.

Accordingly, it is an object of the invention to provide a novel chromatographic column.

It is a further object of the invention to provide a chromatographic column in which the end fittings and sleeves may be removed relatively easily.

It is a still further object of the invention to provide a relatively inexpensive and simply-constructed chromatographic column.

It is a still further object of the invention to provide a chromatographic column which is relatively easily assembled.

It is a still further object of the invention to provide a safe chromatographic column in which the end fittings may be removed relatively easily from either end.

It is a still further object of the invention to provide a chromatographic column having flanges which extend radially at a right angle to the column on both ends and is yet relatively safe to operate.

It is a still further object of the invention to provide a chromatographic column in which the central column has end flanges extending perpendicularly from both ends and end fittings which may be removed relatively easily.

In accordance with the above and further objects of the invention, a chromatographic column includes a,

central glass column having a uniform inside diameter and flanges extending orthogonally. outwardly from each of its ends. Sleeves which have a threaded end to receive end fittings for communication with the central column each include an inner ridge which presses a relatively rigid retaining ring and an O-ring against a flange of the central column, with a different one of two O-rings being between each rigid retaining ring and each end flange to form a fluid seal. The rigid retaining ring is a split ring which may be snapped around the central tube without being pulled over the end flanges and the O-ring is sufficiently elastomeric to be pulled over the end flanges.

With this arrangement, the sleeves are assembled by first inserting them over the central tube and the split retaining ring is assembled around the tube later with the O-ring being pulled over the end flanges and positioned between the split retaining ring and the end flanges. The sleeves are then held onto the central column by the retaining ring which is pressed by the ridge within the sleeves against the O-ring across virtually an entire side of the O-ring so that it cannot be extruded into the clearance between the shoulder of the sleeve and the flanges at the end of the column. The end fittings are threaded into the ends of the sleeves.

As can be understood from the above description, the chromatographic column of this invention has several advantages, such as: l it is relatively inexpensive to fabricate; (2) the central columns are easily replaced if they are broken; and (3) it is relatively safe to use.

The above-noted and other features of this invention will be better understood from the following detailed description when considered with reference to the accompanying drawings in which:

FIG. 1 is a schematic view of a chromatographic analyzing system in accordance with an embodiment of the invention;

FIG. 2 is a fragmentary side view, partly broken away, to show the central column of the chromatographic column of FIG. 1;

FIG. 3 is a perspective view of a portion of the chromatographic column of FIGS. 1 and 2; and

FIG. 4 is a fragmentary, longitudinal, sectional view of the chromatographic column of FIGS.-1 and 2.

In FIG. 1, there is shown a medium-pressure liquid chromatographic analyzing system 10, having a chromatographic column 12, an ultraviolet monitor 14, a fraction collector l6, and a pump system 18.

The inlet of the chromatographic column 12 communicates with the pump system 18, which injects a sample, followed by a solvent, into the chromatographic column for separation of the molecular species of the sample. The outlet of the chromatographic column 12 communicates with the fractioncollector 16 through the ultraviolet monitor 14, which controls the fraction collector in response to different light absorbances of the eluent to deposit different molecular species into different containers.

To inject the sample and pump the solvent, the pump system 18, includes an injection valve 20, a sample pump 22, an inlet conduit 24 and a solvent pump 26.

To inject a sample into the chromatographic column 12, the injection valve 20 causes the sample pump 22 to communicate with the inlet conduit 24 and to apply a sample to the chromatographic column 12 through the end coupling 27. To pump a solvent through the chromatographic column 12, the valve 20 causes communication between the solvent pump 26 and the inlet conduit 24 after the sample has been injected.

To monitor the eluent from'the chromatographic column 12, the ultraviolet monitor 14 is connected at one end to the outlet of the column 12 through the end coupling 28 to receive fluid from the column 12 for moni toring thereof and to pass the fluid to the conduit 30.

To collect the samples, the fraction collector 16 includes a rotatable turntable 32 and a rack 34, which moves a plurality of test tubes 36 underneath the conduit 30 under the control of the monitor 14 to receive samples of the eluent.

To cool the column 12, a water pump 38 pumps water through the conduits 40 and 42 and the water jacket 48 of the chromatographic column 12. To enable the conduits 40 and 42 to communicate with the water jacket 48, connectors 90 and 91 are inserted into an opening 64, as shown in FIG. 2, in the sleeve 50 and into a similar opening in the sleeve 52 respectively to communicate with the interior of the water jacket.

To separate the molecular species of the sample, the chromatographic column 12 includes a central column 46, an outer glass water jacket 48, and top and bottom end couplings 27 and 28. The top and bottom end couplings 27 and 28 include top and bottom sleeves 50 and 52 respectively, top and bottom end fittings 54 and 56 respectively and upper and lower tubular connecting nuts 58 and 60 respectively.

The central column 46 is connected to the conduit 24 at one end through the fluid-tight coupling 27, which includes a continuous passageway through the sleeve 52, the end fitting 56 and the apertured connecting nut 60 is connected to the conduit 30 through the fluidtight coupling 28, which includes parts corresponding to those in the coupling 27.

To control the temperature of the chromatographic column 12, the water jacket 48 fits around the sleeves 50 and 52, being sealed thereagainst by O-rings and communicates with the conduits 40 and 42 through apertures in the sleeves to provide circulating water adjacent to the central column 46 for the cooling thereof.

As best shown in FIG. 2, the sleeve 50 is generally cylindrical in shape, with an outer dimension that is slightly smaller than the inner diameter of the water jacket 48 and includes: (1) an annular groove on its lower outer surface which receives an O-ring 62 to seal it against the inner wall of the Water jacket; (2) a circular opening 64 to communicate with the water jacket; and (3) a central passageway 66 which communicates with the opening 64 and has a threaded cylindrical inner wall 70.

The central column 46 has a uniform inside diameter and a uniform outside diameter, with flanges 72 extending orthogonally outwardly from each of its ends and having the same wall thickness as the column walls for easy forming. Over its outside surface, the column 46 receives against each flange, a different O-ring 74 and a different rigid split retaining ring 76 having inner diameters approximately the size of the column 46, with each O-ring 74 being between a different retaining ring 76 and flange 72.

For convenient assembling, the O-ring is elastomeric and can be stretched over the flange 72 and the two halves 77 and 78 of the ring 76 can be snapped together around the column 46. In a preferred embodiment, the split retaining ring 76, when the two halves are together, forms a torus having an annular cross-section taken through a plane parallel to its longitudinal axis and a rectangular cross-section taken in a transverse plane through the wall at one point.

The term rigid, when used to describe the ring 76,

means that it is fabricated from material having a flexural modulus of 30,000 psi (ASTM, test D 790) or greater.

The ring 76 is formed of two identical interfitting parts 77 and 78, one of which is shown in FIG. 3. Each half of the split ring 76 is generally horseshoe shaped with a portion 80 of greater lateral height and a portion 82 of shorter lateral height, with the portion of greater lateral height of one part complementing the portion of shorter lateral height of the other part so that two such halves fit together with the portions 80 adjacent to the portions 82 to form a solid ring that fits around the central column 46. Each half of the split ring '76 covers more than 180 of arc so that it independently adheres to the column 46 for ease in assembling.

As best shown in FIG. 4, the sleeve 50 includes an inwardly-extending annular ridge 68 concentric with and having a common longitudinal axis with the inner walls of the sleeve 50 from which it extends to an inside diameter slightly larger than the outer. diameter of the flange 72 of the column 46 to enable the separation of the sleeve 50 and the column 46. The ridge 68 is located between the ends of the sleeve 50 and spaced from the threaded wall 70 by a smooth portion sufficiently long to confine the split ring 76 and the O-ring 74.

The end fitting 54 includes a first cylindrical portion 83 having external screw threads that engage the internal threads of the wall 70 and a second cylindrical portion 85 of larger diameter than the first cylindrical portion by which the end fitting is threaded into the sleeve 50 during assembly and which includes a central tapped hole 79.

In this position, the split ring 76 rests against the ridge 68 with the O-ring 74 being between the flange 72 and the split ring 76 to seal the water jacket at this location and to hold the end fitting S4 in place on the column 46. When compressed by this assembly, the

ring 76 applies pressure to the O-ring 74, distorting it to a shape that restrains the sleeve 50 from moving beyond the flange 72.

To connect the ultraviolet scanner 14 (FIG., 1) to the chromatographic column 12, the nut 58 and end fitting 54 each include a central opening 88 to provide communication between the column 46 and a transparent tube 30 which passes through the ultraviolet scanner 14. The nut 58 has a first tubular end 87 threaded into the central threaded hole 79of the end fitting 54, a sec ond tubular end 89 that receives the transparent tube 30, and a separable tubular tightening nut 84 that threads onto the second tubular end 89,, with the transparent tube 30 passing through its center. The tubular nut 84 includes a Teflon or polypropylene ferrule 86 which presses against the tube 30, sealing it to the inner walls of the tube 89 when the nut 84 is tightly threaded onto the tube 89.

The sleeve 52 is substantially the same as the sleeve 50 and will not be separately described. It also cooperates with one end of the central column 46, an O-ring and a split ring. While the split ring 76 in the preferred embodiment has two separable halves, a single ring can be used, which ring would be separable at one point so that its ends can be spaced apart and snapped over the column 46. Moreover, rings composed of more than two parts are also usable, the' principal features being that at least one part of it engage a portion of the sleeve 50 and that it be sufficiently rigid to impart force to the O-ring from the sleeve. i i

The central column 46 and water jacket 48 are preferrably of glass. The sleeve 50 and 52 and fittings are formed of any relatively chemically resistant material such as polyvinyl chloride or the like.

To assemble the chromatographic column- 12 before inserting it into the chromatographic analyzing system 10, the sleeves 50 and 5.2 are placed over the central column46 and the water jacketwall 48 is inserted over them so that its inner surface rests against the O-rings (62 in FIG. 4). With the water jacket 48 and the sleeves 50 and 52 pusheditowa'rd each other to expose the flanges 72 and the portion of the wall of the central column 46 adjacent to it, the O-rin gs 74 are pulled over the flanges 72 (FIGS. 2 and 4), the two halves of the split ring 76 are snapped over the column 46 in a complementary relationship with each other to forma solid ring near the O-ring 74. i

The sleeves 50 and 52 are then pushed forward as far as possible and the end fittings 54 and 56threaded onto their internal threads; to formla solid connector that seals the interior of the tube 46 and permits communication only through the inlet and outlet of the end'fittings. The coupling nuts 58 and 60 are threadedinto the end fittings 54 and 56 respectively, after which, the tubes 30 and 24 are inserted through the central openings of the tightening nut 84 and into the end fitting to cause the tubes 30 and 24 to communicate with the central column 46. The tightening nuts are tightened to seal the outer walls of the tubes 30 and 24 to the end fittings so as to prevent leakage.

To provide circulating water within the water jacket 48, the connectors 90 and 91 (FIG. 1) are inserted into the openings 64 (FIG. 4) in the sleeves 50 and 52 and are connected with the conduits 40 and 42, which receive water circulated by the pump 38.

The chromatographic column 12 is mounted in a stand, with the monitor 14 and the fraction collector 16 connected to it. The pump assembly 18 is then ready to insert a sample and to separate the molecular species of the sample by pumping the fluid from the pump 22 upwardly through the properly packed chromatographic column 12.

In operation, pressure within the column 12, may reach 200 pounds per square inch and presses outwardly on the end fittings 54 and 56. When this pressure is applied to the end fittings 54 and 56, the ridge 68 exerts pressure against the split rings 76 which press the O-rings 74 against the flanges 72, distorting the 0- rings so that they tightly fill the space between the flanges 72, the surfaces of the central column 46, the inner surfaces of the sleeves and the surfaces of the split rings 76. Since the split rings 76 are relatively rigid, they do not extrude through the clearance space between the ridge 68 and the flange 72 to permit passage of the flange 72 past the ridge 68.

The end fittings 54 and 56 are held to the sleeves 50 and 52 by the threads 70 and the sleeves are prevented from being forced off the column 46 by the flanges 72 which hold the split rings 76 and the O-rings 74 against the ridge 68 of the sleeves 50 and 52. With the sleeves 50 and 52 held securely in place, the end fittings are also prevented from being forced from the water jacket wall 48.

With this arrangement, the end fittings are easily assembled and replaced. If the central column 46 is broken, both of the end fittings 54 and 56 is unthreaded, the O-rings 74 pulled over the flange 72 and the split rings 76 removed by pulling the two halves 77 and 78 off the column 46. Once this is done, the sleeves 50 and 52 are slipped off the ends of the column 46 and the entire assembly isdismantled. The broken parts are then replaced and a new assembly formed as described here and above.

As can be understood from this description, the chromatographic column of this invention has several advantages, such as: (1) it is inexpensively (formed; (2) the central columns are easily replaced 'if broken; and (3) the chromatographic column is relatively safe to use.

Although a preferred embodiment has been described with some particularity, many modifications and variations in the embodiment may be made without deviating from the invention. Accordingly, it .is to be understood that, within the scope of the appended claims, theinvention may be practiced other than as specifically described.

What is claimed is:

1. An apparatus comprising:

a central tubular column;

said central tubular column having a at one end;

sealing means having an inner surface with substantially the same shape and size as the outer surface of said central cylindrical column along a closed path adjacent to said flange and adapted to be positioned around said tubular column adjacent to said flange;

the outer diameter of said sealing means being greater than the outer diameter of said flange and the inner diameter being approximately the same as the diameter of said central tube and less than the outer diameter of said flange;

at least one portion of said sealing means being rigid;

a sleeve having an'edge with an inner diameter sufficiently large to fit over said flange and sufficiently small to contact said sealing means;

said sealing means being removable from said column;

said sleeve including means for fastening an end fitting thereto in communication with the center of said central tube.

2. An apparatus according to claim 1 further comprising:

a second flange at a second end of said central tubular column;

a second sealing means having an inner surface with substantially the same shape and size as the outer surface of said central tubular column along a closed path adjacent to said flange and adapted to be positioned around said central tubular column adjacent to said flange;

the outer diameter of said second sealing means being greater than the outer diameter of said flange and the inner diameter being approximately the same as the diameter of said ce tral tubular column and less than the outer diameter of said flange;

at least one portion of said second sealing means being rigid;

flange at least a sleeve having an edge with an inner diameter sufficiently large to fit over said flange and sufficiently small to contact said second sealing means; i

said second sealing means being removable from said central tubular column; and

said sleeve including means for fastening an end fitting thereto in communication with the center of said central tubular column. 3. Apparatus according to claim 2 in which said sealing means comprises:

an elastomeric sealing ring adapted to be positioned around said central tubular column adjacent to said flange and having an inner diameter less than and an outer diameter greater than the outer diameter of said flange; and 1 rigid means for rigidly connecting the inner edge of said central tubular column to said elastomeric sealing ring.

4. Apparatus according to claim 3 in which said rigid means includes a ring, said ring having two adjoining portions which are separable from each other, whereby said ring may be forced around said central tubular column without passing over said flange.

5. Apparatus according to claim 4 in which said adjoining portions each include internal walls defining an are greater than 180.

6. Apparatus according to claim 5 in which said central tubular column is glass.

7. Apparatus according to claim 6 further including an outer glass tube, said outer glass tube having an inner diameter slightly larger than the outer diameter of said sleeve, whereby said outer glass tube may be positioned with its longitudinal axis coincident with the longitudinal axis of said central tubular column and its ends contacting said first and second sleeves to form a water jacket.

8. Apparatus according to claim 7 in which said sleeves include internal walls defining openings communicating with the inside of said water jacket.

9. Apparatus according to claim 8 further including end fittings adapted to be connected to said sleeves.

10. Apparatus according to claim 1 in which said sealing means comprises:

an elastomeric sealing ring adapted to be positioned around said central tubular column adjacent to said flange and having an inner diameter less than and an outer diameter greater than the outer diameter of said flange; I said central tubular column having an inner edge;

and rigid means for rigidly connecting said inner edge of said central tubular column to said elastomeric sealing ring. 11. Apparatus according to claim 10 in which said rigid means includes a ring, said ring having two adjoining portions which are separable from each other, whereby said ring may be forced around said central tubular column without passing over said flange.

12. Apparatus according to claim 11 in which said adjoining portions each include internal walls defining an arc greater than 180.

13. Apparatus according to claim 12 in whichtsaid central tubular column is glass.

14. Apparatus according to claim 13 further including end fittings adapted to be connected to said. sleeves.

15. Apparatus according to claim 1 further including end fittings adapted to be connected to said sleeves.

16. Apparatus according to claim 1 in which said flange is of substantiallythe same thickness as the walls of the central tubular column.

17. Apparatus according to claim 2 in which said flanges are of substantially the same thickness as the walls of the centralt ubular column.

18. Apparatus according to claim 10 in which said flange is of substantially the. same thickness as the walls 

1. AN APPARATUS COMPRISING: A CENTRAL TUBULAR COLUMN, SAID CENTRAL TUBULAR COLUMN HAVING A FLANGE AT LEAST AT ONE END, SEALING MEANS HAVING AN INNER SURFACE WITH SUBSTANTIALLY THE SAME SHAPE AND SIZE AS THE OUTER SURFACE OF SAID CENRAL CYLINDRICAL COLUMN ALONG A CLOSED PATH ADJACENT TO SAID FLANGE AND ADAPTED TO BE POSITIONED AROUND SAID TUBULAR COLUMN ADJACENT TO SAID FLANGE, THE OUTER DIAMETER OF SAID SEALING MEANS BEING GREATER THAN THE OUTER DIAMETER OF SAID FLANGE AND THE INNER DIAMETER BEING APPROXIMATELY THE SAME AS THE DIAMETER OF SAID CENTRAL TUBE AND LESS THAN THE OUTER DIAMETER OF SAID FLANGE, AT LEAST ONE PORTION OF SAID SEALING MEANS BEING RIGID, A SLEEVE HAVING AN EDGE WITH AN INNER DIAMETER SUFFICIENTLY LARGE TO FIT OVER SAID FLANGE AND SUFFICIENTLY SMALL TO CONTRACT SAID SEALING MEANS, SAID SEALING MEANS BEING REMOVABLE FROM SAID COLUMN, SAID SLEEVE INCLUDING MEANS FOR FASTENING AN END FITTING THERETO IN COMMUNICATION WITH THE CENTER OF SAID CENTRAL TUBE.
 2. An apparatus according to claim 1 further comprising: a second flange at a second end of said central tubular column; a second sealing means having an inner surface with substantially the same shape and size as the outer surface of said central tubular column along a closed path adjacent to said flange and adapted to be positioned around said central tubular column adjacent to said flange; the outer diameter of said second sealing means being greater than the outer diameter of said flange and the inner diameter being approximately the same as the diameter of said central tubular column and less than the outer diameter of said flange; at least one portion of said second sealing means being rigid; a sleeve having an edge with an inner diameter sufficiently large to fit over said flange and sufficiently small to contact said second sealing means; said second sealing means being removable from said central tubular column; and said sleeve including means for fastening an end fitting thereto in communication with the center of said central tubular column.
 3. Apparatus according to claim 2 in which said sealing means comprises: an elastomeric sealing ring adapted to be positioned around said central tubular column adjacent to said flange and having an inner diameter less than and an outer diameter greater than the outer diameter of said flange; and rigid means for rigidly connecting the inner edge of said central tubular column to said elastomeric sealing ring.
 4. Apparatus according to claim 3 in which said rigid means includes a ring, said ring having two adjoining portions which are separable from each other, whereby said ring may be forced around said central tubular column without passing over said flange.
 5. Apparatus according to claim 4 in which said adjoining portions each include internal walls defining an arc greater than 180*.
 6. Apparatus according to claim 5 in which said central tubular column is glass.
 7. Apparatus according to claim 6 further including an outer glass tube, said outer glass tube having an inner diameter slightly larger than the outer diameter of said sleeve, whereby said outer glass tube may be positioned with its longitudinal axis coincident with the longitudinal axis of said central tubular column and its ends contacting said first and second sleeves to form a water jacket.
 8. Apparatus according to claim 7 in which said sleeves include internal walls defining openings communicating with the inside of said water jacket.
 9. Apparatus according to claim 8 further including end fittings adapted to be connected to said sleeves.
 10. Apparatus according to claim 1 in which said sealing means comprises: an elastomeric sealing ring adapted to be positioned around said central tubular column adjacent to said flange and having an inner diameter less than and an outer diameter greater than the outer diameter of said flange; said central tubular column having an inner edge; and rigid means for rigidly connecting said inner edge of said central tubular column to said elastomeric sealing ring.
 11. Apparatus according to claim 10 in which said riGid means includes a ring, said ring having two adjoining portions which are separable from each other, whereby said ring may be forced around said central tubular column without passing over said flange.
 12. Apparatus according to claim 11 in which said adjoining portions each include internal walls defining an arc greater than 180*.
 13. Apparatus according to claim 12 in which said central tubular column is glass.
 14. Apparatus according to claim 13 further including end fittings adapted to be connected to said sleeves.
 15. Apparatus according to claim 1 further including end fittings adapted to be connected to said sleeves.
 16. Apparatus according to claim 1 in which said flange is of substantially the same thickness as the walls of the central tubular column.
 17. Apparatus according to claim 2 in which said flanges are of substantially the same thickness as the walls of the central tubular column.
 18. Apparatus according to claim 10 in which said flange is of substantially the same thickness as the walls of the central tubular column. 